Wet abrasive blast pot

ABSTRACT

A wet abrasive blast pot includes a cylindrical pressure vessel have a top section, a bottom section, and sidewalls extending between the top section and the bottom section. The bottom section includes an outlet, and the top section includes a fill inlet. The top section includes a convex head, with the fill inlet located at the uppermost portion of the pressure vessel.

BACKGROUND

Wet abrasive blasting systems are typically used in situations requiring blasting operations that do not tolerate dry sandblasting conditions due to environmental or other factors. Wet abrasive blasting systems are used to control generation of dust and at the same time ensure that there is minimal damage to the substrate. Wet abrasive blasting systems force a slurry of abrasive media into a compressed airstream under controlled conditions. A blast pot or pressure vessel is charged with water and a solid abrasive to form a wet abrasive slurry. It is very important that the blast pot be purged of air prior to commencement of the blasting operation. The pressurized water forces the slurry out of the blast pot, into a piping system, and finally into a mixing point where the wet slurry is mixed with compressed air. Fluctuations in flow of pressure in either the slurry or pressurized gas will result in inconsistent behaviour of the wet abrasive blasting system and ultimately will lead to an uncontrollable or inefficient blasting process. It has been found that air entrapment in the blast pot or pressure vessel is a major contributing factor to instability of wet abrasive blasting systems. In systems to date, air relief valves have been employed in order to purge the blast pot or pressure vessel of all air prior to pressurizing with water. Unfortunately these air bleeding or purging systems often require two to three minutes of time to completely evacuate the blast pot or pressure vessel of air thereby reducing the efficiency of the wet abrasive blasting operation.

It would be best and beneficial if one were able to utilize a blast pot pressure vessel design which eliminates the entrapment of air and therefore reduces or eliminates the need for bleeding of entrapped air in the pressure vessel prior to commencement of the blasting operation.

SUMMARY

A wet abrasive blast pot includes a cylindrical pressure vessel having a top section, a bottom section, and sidewalls extending between the top section and the bottom section. The bottom section includes an outlet, and the top section includes a fill inlet. The top section includes a convex head, with the fill inlet located at the uppermost portion of the pressure vessel.

Preferably, the top section further includes a concave dish top, wherein a lower most portion of the concave dish top is connected to the upper most portion of the convex head at the fill inlet. The top section also preferably includes connecting walls for connecting the sidewalls to the outer most portion of the concave dish top.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional schematic view of a prior art blast pot with a concave head configuration.

FIG. 2 is a schematic cross-sectional view taken through the middle of a blast pot showing a convex head configuration.

FIG. 3 is a schematic cross-sectional view taken through the middle of a blast pot showing a convex head configuration together with a concave dish extension.

FIG. 4 is a schematic of a wet abrasive blasting system including the blast pot of FIG. 3.

DETAILED DESCRIPTION

FIG. 1 is a prior art depiction of a typically currently used wet abrasive blast pot 100 which includes the following major components: pressure vessel 102 having side walls 104, concave top section 106, bottom section 108, outlet 110, and fill inlet 112.

Furthermore, pressure vessel 102 defines interior 114 and also includes pop up valve 116, access port 118 for cleaning out the pressure vessel, air pressure release valve 120 (which allows trapped air 124 to be expelled as air 122), and water level 126. Blast pot 100 further includes legs 130 which support pressure vessel 102 and dished top section 106 which includes concave head 128.

In use, prior art blast pot 100 is filled with abrasive and water through fill inlet 112 until interior 114 of pressure vessel 102 is filled as high as is possible, which normally would be close to water level 126 shown in FIG. 1. Top section 106 is made up of dished concave head 128. Due to the geometric configuration of concave head 128, air 122 is trapped as trapped air 124 in the space above water level 126 and below concave head 128 as shown in FIG. 1.

Due to the location of fill inlet 112, under gravity filling it is difficult to get the water and abrasive in pressure vessel 102 any higher than water level 126. Once abrasive and water is filled to water level 126, pop up valve 116 is closed, and then purging of trapped air 124 is commenced.

At this point, blast pot 100 is pressurized with pressurized water. Air release valve 120 allows trapped air 124 to be released and expelled from interior 114 of pressure vessel 102 as air 122 until such time as water level 126 reaches fill level 132, which is the upper most point defined where sidewall 104 meet the upper most portion of concave head 128.

Blast pot 100 uses an inverted or concave head 128 which functions not only as a top to pressure vessel 102, but also acts as a funnel and/or dish hopper for directing the blasting abrasive material and water into fill inlet 112 of blast pot 100.

The disadvantage of the prior art design depicted in FIG. 1 is that concave head 128 entraps trapped air 124 above fill inlet 112 of blast pot 100. Therefore blast pot 100 must be fitted with air release valve 120 to allow trapped air 124 to escape as air 122. This purging or bleeding of trapped air 124 can take upwards of two to three minutes and result in reduced productivity of the wet abrasive blasting system.

FIG. 2 shows blast pot 200, which includes the following major components: pressure vessel 202 which defines an interior 214 made up of side walls 204, top section 250, bottom section 108 (which includes an outlet 110 at the bottom section 108), and fill inlet 112 at top section 250. Unlike prior art blast pot 100, blast pot 200 includes a convex-shaped convex head 252.

In use, abrasive and water is filled into fill inlet 112. Due to the configuration of convex head 252 as shown in FIG. 2, water and abrasive can be filled all the way up to fill level 232 (which is at least the bottom of fill inlet 112), thereby ensuring that there is little to no entrapped air within pressure vessel 202 once water and abrasive is filled all the way to the top to fill level 232.

A disadvantage of this design is that there is no funnel or dish hopper configuration at the top section 250 which would funnel water and abrasive into the pressure vessel 202. This could result in a significant amount of spillage and waste of both the abrasive material and water.

FIG. 3 shows blast pot 300, which includes the following major components: namely, pressure vessel 302, made of side wall 304, bottom section 108 including outlet 110, top section 370 (which includes convex head 252, and connecting wall 362), and concave dish top 360. Blast pot 300 also includes fill inlet 112, pop up valve 116, and access port 118.

In this embodiment, blast pot 300 includes all the advantages described above for blast pot 200 with the addition of a concave dish top which connects at fill inlet 112 with convex head 252 and is supported by connecting wall 362. Blast pot 300 does not entrap any air due to the fact that at fill level 380 most if not all of the air has been purged from interior 214 of pressure vessel 302 through fill inlet 112, which is at the uppermost point of pressure vessel 302. Blast pot 300 however also includes the advantage of the prior art blast pot design 100 section since it includes a concave dish top 360 which acts as a funnel and/or a dish hopper for directing abrasive material and water into the fill inlet of pressure vessel 302.

FIG. 4 is a schematic diagram of an abrasive wet blasting system utilizing blast pot 300, which includes the following additional components not shown in FIG. 3. Water pump 400 (which preferably is a pneumatic air over water piston pump) takes water supply 402 and pressurizes it and sends it under pressure to water inlet 404, thereby pressurizing water abrasive mixture 406 within interior 214 of pressure vessel 302. Water abrasive mixture 406 is a slurry which is forced out through outlet 110 and through transfer hose 410 up through ball valve 412 and through pinch hose 416, which can be shut off with pinch valve 414 prior to water abrasive mixture 406 entering T connector 418 at mixing point 420.

Independently, air supply 422 delivers compressed air (typically from a high volume air compressor) through air valve 424, and check valve 421 to mixing point 420. At mixing point 420, the compressed air mixes together with the water abrasive mixture 406 and is forced out through blast hose 426 and ultimately through blast nozzle 428, thus forming an air water abrasive blast 430 out of blast nozzle 428.

FIG. 4 shows schematically how the newly conceived of blast pot 300 would be used together with a typical wet abrasive blasting system.

It is also possible that blast pot 200 could be used in a similar configuration as shown in FIG. 4.

It should be apparent to persons skilled in the arts that various modifications and adaptation of this structure described above are possible without departure from the spirit of the invention the scope of which defined in the appended claim. 

1. A blast pot for use in wet abrasive blasting systems, the blast pot comprising: a cylindrical pressure vessel which includes sidewalls, a bottom section and a top section; wherein the bottom section includes an outlet; wherein the top section includes a convex head; and wherein the convex head includes a fill inlet located at an upper most portion of the pressure vessel.
 2. The blast pot claimed in claim 1 wherein the top section further includes a concave dish top, and wherein a lower most portion of the concave dish top is connected to the upper most portion of the convex head at the fill inlet.
 3. The blast pot claimed in claim 2 wherein the top section further includes connecting walls that connect the sidewalls to an outer most portion of the concave dish top.
 4. A blast pot for use in wet abrasive blasting systems, the blast pot comprising: a cylindrical pressure vessel which includes: a bottom section; an outlet in the bottom section; a convex head; a fill inlet located at an upper most portion of the convex head; and sidewall extending between the bottom section and the convex head; and a concave dish top mounted on the convex head, wherein a lower most portion of the concave dish top is connected to the upper most portion of the convex head at the fill inlet.
 5. The blast pot claimed in claim 4 and further comprising: connecting walls that connect the sidewalls to an outer most portion of the concave dish top. 